1. Field of the Invention
The invention relates to ion-selective electrodes and, specifically, to the structure and manufacture of an ion-specific electrode of compact size, yet including both sensing and reference electrodes.
2. Background Information
Ion-selective electrodes of various types are used to measure the concentration of ions in solution. Particularly useful electrodes are those which include both a sensing electrode and a reference electrode in a single unit; this type of electrode is commonly referred to as a “combination electrode”. An example of such an electrode is described in U.S. Pat. No. 6,793,787, issued Sep. 21, 2004 to Moshe Hirshberg et al.
With the advent of large-scale testing of biological samples in very small sample vessels, a need has arisen for ion-selective electrodes which can be accommodated in such vessels. For example, one type of frequently-used sample vessel has 96 wells of dimensions 8 mm (millimeters) by 10 mm. The accommodation of ion-specific electrodes to such small volumes is challenging.